This invention relates to an apparatus and method for cleaning air filter elements and more particularly to an apparatus and method for loosening and removing dust accumulated in an air filter element after a period of use of the filter.
Dust inducted with air into the cylinders of an internal combustion engine is one of the major causes of short engine life, high fuel consumption and expensive repairs. Once dirt enters the cylinders, it finds its way into the piston ring grooves, oil passages, bearings and other working parts.
The filter elements used in heavy-duty, large scale equipment such as the graders, trucks and other units used in road construction and mining operations are considerably larger and more costly than the air filters commonly used in passenger automobiles and other relatively small vehicles. Because such equipment is customarily exposed to conditions involving high levels of air-borne particulate matter, frequent cleaning or replacement of the filter elements is required in order to prevent engine damage and maintain operating efficiency.
Almost all heavy equipment owners have been faced with one of two alternatives to complete replacement; namely, either wet or dry cleaning and subsequent reinstallation. The owner could send the filters to a commercial washing plant which was effective but expensive requiring replacement of the filters after two or three washings as well as a substantial stock of spare filters. The owner could also attempt to clean the filter elements with a compressed air hose but the filter element was often damaged without any way of assuring that it was clean. With these consequences in mind, the heavy equipment owner found neither wet nor dry cleaning and reinstallation of the filter elements to be entirely satisfactory.
Subsequently, a motor driven vacuum confined to a narrow segment of the filter elements was developed. The air flowed through the filter elements in reverse of the normal flow, spread the pleats, opened the inner folds, and sucked out the collected grit and dirt. Both in-to-out and out-to-in filter elements could be dry cleaned by slowly rotating them relative to the vacuum tapping lightly to dislodge persistent particles.
Since controlled air vacuuming did not hurt the paper filter element, the filters could be cleaned in this manner between 20 to 30 times before discarding. On the other hand, according to industry representatives, when a filter element is washed the first time, it looses approximately 30% of its capacity usually requiring the element to be discarded after three or four launderings. The utility of dry cleaning filter elements has clearly been established in the field leaving those skilled in the art to seek even more effective dry cleaning method and apparatus.
The prior art is exemplified by U.S. Pat. Nos. 3,004,276; 3,373,552; and 3,888,694. Co-owned U.S. Pat. No. 3,004,276 reveals an earlier construction of the dry cleaning type. The present invention represents an improvement upon prior art constructions.